Alkoxy(poly)alkylene glycols, for example, esterified with such an unsaturated monomer as (meth)acrylic acid, give (meth) acrylic ester monomers, which are used suitably as raw materials for cement additive polymer. In cases the alkoxy(poly)alkylene glycols are unsaturated alcohol-alkylene oxide adducts, they can also be used as raw materials for cement additive polymer. Such cement additive polymers can suitably be used not only as cement additives (cement dispersants) but also as dispersants for pigments such as calcium carbonate, carbon black and ink, scaling inhibitors, dispersants for gypsum-water slurries, dispersants for coal-water slurries (CWMs), thickening agents and like chemical products.
Meanwhile, alkoxy(poly)alkylene glycols are produced, for example, by subjecting an alcohol and an alkylene oxide, such as ethylene oxide and propylene oxide to addition under alkaline conditions. Such alkoxy(poly)alkylene glycols generally stored and/or transferred in a vessel before they are used as raw materials for cement additive polymer. For example, they are stored for a while or for along time before until polymer production or, when the plant for alkoxy(poly)alkylene glycol production is remote from the plant for monomer or polymer production, they are to be transferred.
However, alkoxy(poly)alkylene glycols generally used as raw materials for polymer production are readily oxidizable in an atmosphere of air. When they occur as solid at ordinary temperature, such alkoxy(poly)alkylene glycols are filled into vessels while they are still at high temperatures after production thereof by alkylene oxide addition to alcohols and therefore still occur as liquids and, for making it easy to draw out them from the vessels, they are stored and/or transferred in a heat insulation so that they may remain in a liquid state. When maintained at an elevated temperature for a certain period, the alkoxy(poly)alkylene glycols will be oxidized, resulting in increases of peroxide value (POV) and, in the case of alkoxy(poly)alkylene glycols having an unsaturated bond, polymerization reactions may occur, leading to form gel-like matter formation. In cases where the alkoxy(poly)alkylene glycols are converted to (meth) acrylic ester monomers by esterificating with (meth) acrylic acid, too, the possibility of gel-like matter formation during the esterification becomes high. Furthermore, the alkylene oxide adducts may be thermally decomposed or, in the case of (meth) acrylic ester monomers, these may also be hydrolyzed. The reaction formula illustrating the thermal decomposition of an unsaturated alcohol-alkylene oxide adduct and the reaction formula illustrating the hydrolysis of a (meth) acrylic ester monomer are shown below by way of example as formulas (1) and (2):H2C═C(R)CH2CH2O(CH2CH2O)nH→H2C═CH(R)CH═CH2+HO(CH2CH2O)nH  (1)H2C═C(R)CO(OCH2CH2)nOCH3+H2O→H2C═C(R)COOH+H(OCH2CH2)nOCH3  (2)
Such troubles occurring during storage and/or transfer of an alkoxy(poly)alkylene glycol result in a decreased purity of the polymer produced therefrom, in an increased impurity content, hence a deterioration in quality thereof, and/or in a deterioration in quality or performance of the chemical product produced from such polymer. For example, if an unsaturated alcohol-alkylene oxide adduct is thermally decomposed, the desired molecular weight will not be obtained any longer in producing cement additive polymer therefrom. Further, if such polymer is used in preparing a cement additive, the content of polyethylene glycol (PEG), which causes an increased air content in cement compositions, will increase, possibly causing troubles such as decreases in strength due to increased air contents in hardened cement structures and, in addition, the content of the active ingredient polymer will decrease, resulting in decreases in the water reducing and other performance characteristics required of the cement dispersant. Furthermore, in cases where R in the above formula (1) is H, for instance, isoprene may be produced; the odor of isoprene will impair the working environment or the product isoprene will be polymerized to form impurities or copolymerized with the intended polymer to lower performance characteristics of the product.
A cement additive containing cement additive polymer derived from an alkoxy(poly)alkylene glycol improves the flow ability of a cement composition and, at the same time, improve the strength and durability of hardened products. When, however, it is contaminated with impurities or the polymer is deteriorated in its performance characteristics or quality, the resulting hardened products, such as civil engineering or building structures, may show lowered levels of strength and durability, whereby such problems as decreased safety and/or increases in repairing cost may possibly be caused.
In JP Kokai 2000-154049, there is disclosed a storing and/or transferring method of alkoxypolyalkylene glycols in vessels in an inert gas-substituted atmosphere and/or with a radical scavenger added. However, there is room for further investigation concerning the temperature and pressure in the steps of filling, storing/transferring and drawing out.
It is an object of the present invention, which has been made in view of the above-mentioned state of the art, to provide a storing and/or transferring method of an alkoxy(poly)alkylene glycol-containing material for cement additive polymer by which the gel-like matter formation and/or decomposition reaction can be satisfactorily inhibited and, as a result, troubles can be prevented from occurring in the production process and the performance characteristics or quality of cement additive and various chemical products can be satisfactorily prevented from being deteriorated.